Acta Veterinaria et Zootechnica Sinica ›› 2019, Vol. 50 ›› Issue (12): 2498-2508.doi: 10.11843/j.issn.0366-6964.2019.12.014

• PREVENTIVE VETERINARY MEDICINE • Previous Articles     Next Articles

Analysis of Drug Resistance Phenotype, Drug Resistance Genes and Cloned Flora of 62 Mink-derived Escherichia coli Isolates

JIANG Zhiyu1, WANG Fan1, YANG Yi2, YI Shoujing1, YANG Jie1, JU Zijing1, SONG Yan1, ZHU Guoqiang2, SUN Shuhong1,3,4*   

  1. 1. Shandong Agricultural University, Tai'an 271000, China;
    2. College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, China;
    3. Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Tai'an 271000, China;
    4. Shandong Provincial Engineering Technology Research Center of Animal Disease Control and Prevention, Tai'an 271000, China
  • Received:2019-04-15 Online:2019-12-23 Published:2019-12-20

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Abstract: This experiment was conducted to investigate the apparent characteristics and molecular characteristics of Escherichia coli isolates from the feces of a mink farm in Zhucheng. Mink feces from the mink farm were collected for isolating E. coli strains, then the isolates were identified, and their serotypes and drug resistance phenotypes to 14 common antibacterial drugs were determined. The drug resistance genes and the carrying status of the Ⅰ integron gene cassette of these E. coli isolates were detected by using PCR. Multi-locus sequence typing (MLST) was used to analyze the clonal relationship of these strains,and a phylogenetic tree was constructed to analyze the genetic similarity of the same clonal strains. The results showed that 62 strains of E. coli were isolated from 82 samples of mink feces, with a separation rate of 75.61%, and the resistance rate of E. coli isolates to AMP and TET exceeded 90%, and the multidrug-resistant strain (MDR) accounted for 85.48%. Five drug-resistant genes were detected by PCR, and the detection rate of qnrS was the highest (61.29%,38/62). The aaC2, aaC4, sul1 and aac(6')-Ib-cr resistance genes were consistent with the corresponding resistance of these strains (P<0.01). The dominant structure of the class Ⅰ integron variable region in the isolated strain was dfrA27-aadA2-qnrA. The pathogenic serotype was identified and the corresponding strains had multiple drug resistance. The dominant serotype was O104:H4. There were 33 STs in the isolates, and ST46 was the dominant ST (16.13%). There were 3 main clones, CC10, CC46 and CC176, respectively. The STs strains associated with pathogenicity share a common genetic background with human E. coli. The results showed that the mink of the farm were contaminated by pathogenic and multi-drug resistant E. coli. The distribution of drug resistance genes in the same clonal strains showed significant differences in polymorphism and epigenetic characteristics.

Key words: Escherichia coli from mink, pathogenic serotype, drug resistance gene, clonal complexes, phylogenetic tree

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